BTEC Applied Science Level 3 National Extended Diploma Unit 2: Practical Scientific Procedures and
Techniques
Learning Aim A: Undertaking titration and colorimetry to determine the concentration of solutions
By Zohal Nadeem
Keeping up your standards
TITRATION:
Part 1: Preparation of a standard solution
INTRODUCTION:
I am a newly appointed technical assistant at Chemcalequip and as part of the induction period, I
must demonstrate skills that I have learnt in a range of practical procedures and techniques. As part
of my role, I had to make sure all equipment is calibrated, equipment and chemicals are safety
checked because I conducted titration and colorimetry procedures. I have made and tested standard
solutions using the titration and colorimetry procedures in a skilled and accurate way. Through my
practical skills, I have produced a scientific report containing the results, calculations, evaluation of
the techniques and the possible improvements to demonstrate the maintenance of accuracy
throughout the experiment.
Titration is defined as the procedure of determining the concentration of an unknown solution using
a solution of known concentration. Titration (also known as titrimetry) is a common analytical
technique used in industrial laboratories (1) and the manufacturing sector such as chemical and
pharmaceutical manufacturing. A standard solution is a known concentration that is used to conduct
titration techniques and is used in quantitative analysis (1). Quantitative analysis is used in a practical
experiment and numerical results are made. The numerical results are measurable quantities
compared to qualitative analysis which produces unmeasurable quantities such as colour, odour and
transparency (observable results).
A standard solution is made by dissolving an accurately weighed mass of sodium carbonate (solid) in
a known volume of solvent (distilled water) using a volumetric flask. Then we are able to get the
accurate standardisation of a given concentration of hydrochloric acid (HCl) by titration with the
primary standard solution of Na2Co3 and using a calibrated pipette. It is important to ensure all
equipment is calibrated for titrations to accurately determine the concentration of a solution of
sodium hydroxide. The equipment includes the weighing balance, the pH meter (using buffer
solutions) and the pipette.
A weighing balance or scale can be calibrated using specific standard weights such as 50g, 25g, 20g,
100g. The difference between the measured value (the reading) and the true value shows the error.
To minimise the error, we adjust the weighing scale.
RISK ASSESSMENT:
Before the experiment started, we wore PPE (personal protective equipment) to prevent injuries and
for protection from risks. The PPE we wore were lab-coats and eye wear (goggles). The hazard is
glassware and broken glassware could lead to cuts and bleeding. Therefore, we have to make sure
,we handle the beakers and volumetric flask with caution. If there was broken glassware, the teacher
must be contacted immediately and the glassware must not be touched. The sodium carbonate is a
known irritant and can cause eye irritation so we have to wear eye goggles to avoid contact with
eyes. Also, bags had to be kept in the shelf and chairs had to be tucked under the table to prevent
tripping hazards and injuries. The weighing balance has a potential electrical shock hazard so the
weighing balance must not be touched when exposed. Medical advice must be sought if a student is
shocked.
METHOD:
The method has been extracted from the learning aim A section from my lab book, given in Miss
Ajaelu’s lessons.
1. Weigh out 2.65g of sodium carbonate (s) using a spatula. We made sure the lid on the
sodium carbonate is on when not in use to prevent contamination
2. Using a calibrator, zero (tare) the balance with the empty, clean and dry weighing boat
3. Transfer the sodium carbonate carefully to a 250 ml beaker and dissolve with 100 cm 3
distilled water. We made sure the weighing boat had transferred all the powder by washing
out the weighing boat with distilled water
4. A glass rod was used to stir the contents of the beaker until all the sodium carbonate
dissolves
5. Using a funnel, we transferred the solution carefully into a 250 ml volumetric flask. We
washed the stirring rod out to ensure all the solution is transferred. Also, we rinsed the
beaker and funnel into the same volumetric flask using distilled water.
6. Fill the volumetric flask with the solution up to the 250 cm 3 line. We read from the bottom of
the meniscus to make sure accuracy was maintained
7. Stopper the volumetric flask and shake the contents of the flask carefully and then we
labelled our standard solution
, Figure 1: The exact amount of 2.65 g of sodium carbonate (s) in a weighing boat on the weighing
scale (calibrated)
Techniques
Learning Aim A: Undertaking titration and colorimetry to determine the concentration of solutions
By Zohal Nadeem
Keeping up your standards
TITRATION:
Part 1: Preparation of a standard solution
INTRODUCTION:
I am a newly appointed technical assistant at Chemcalequip and as part of the induction period, I
must demonstrate skills that I have learnt in a range of practical procedures and techniques. As part
of my role, I had to make sure all equipment is calibrated, equipment and chemicals are safety
checked because I conducted titration and colorimetry procedures. I have made and tested standard
solutions using the titration and colorimetry procedures in a skilled and accurate way. Through my
practical skills, I have produced a scientific report containing the results, calculations, evaluation of
the techniques and the possible improvements to demonstrate the maintenance of accuracy
throughout the experiment.
Titration is defined as the procedure of determining the concentration of an unknown solution using
a solution of known concentration. Titration (also known as titrimetry) is a common analytical
technique used in industrial laboratories (1) and the manufacturing sector such as chemical and
pharmaceutical manufacturing. A standard solution is a known concentration that is used to conduct
titration techniques and is used in quantitative analysis (1). Quantitative analysis is used in a practical
experiment and numerical results are made. The numerical results are measurable quantities
compared to qualitative analysis which produces unmeasurable quantities such as colour, odour and
transparency (observable results).
A standard solution is made by dissolving an accurately weighed mass of sodium carbonate (solid) in
a known volume of solvent (distilled water) using a volumetric flask. Then we are able to get the
accurate standardisation of a given concentration of hydrochloric acid (HCl) by titration with the
primary standard solution of Na2Co3 and using a calibrated pipette. It is important to ensure all
equipment is calibrated for titrations to accurately determine the concentration of a solution of
sodium hydroxide. The equipment includes the weighing balance, the pH meter (using buffer
solutions) and the pipette.
A weighing balance or scale can be calibrated using specific standard weights such as 50g, 25g, 20g,
100g. The difference between the measured value (the reading) and the true value shows the error.
To minimise the error, we adjust the weighing scale.
RISK ASSESSMENT:
Before the experiment started, we wore PPE (personal protective equipment) to prevent injuries and
for protection from risks. The PPE we wore were lab-coats and eye wear (goggles). The hazard is
glassware and broken glassware could lead to cuts and bleeding. Therefore, we have to make sure
,we handle the beakers and volumetric flask with caution. If there was broken glassware, the teacher
must be contacted immediately and the glassware must not be touched. The sodium carbonate is a
known irritant and can cause eye irritation so we have to wear eye goggles to avoid contact with
eyes. Also, bags had to be kept in the shelf and chairs had to be tucked under the table to prevent
tripping hazards and injuries. The weighing balance has a potential electrical shock hazard so the
weighing balance must not be touched when exposed. Medical advice must be sought if a student is
shocked.
METHOD:
The method has been extracted from the learning aim A section from my lab book, given in Miss
Ajaelu’s lessons.
1. Weigh out 2.65g of sodium carbonate (s) using a spatula. We made sure the lid on the
sodium carbonate is on when not in use to prevent contamination
2. Using a calibrator, zero (tare) the balance with the empty, clean and dry weighing boat
3. Transfer the sodium carbonate carefully to a 250 ml beaker and dissolve with 100 cm 3
distilled water. We made sure the weighing boat had transferred all the powder by washing
out the weighing boat with distilled water
4. A glass rod was used to stir the contents of the beaker until all the sodium carbonate
dissolves
5. Using a funnel, we transferred the solution carefully into a 250 ml volumetric flask. We
washed the stirring rod out to ensure all the solution is transferred. Also, we rinsed the
beaker and funnel into the same volumetric flask using distilled water.
6. Fill the volumetric flask with the solution up to the 250 cm 3 line. We read from the bottom of
the meniscus to make sure accuracy was maintained
7. Stopper the volumetric flask and shake the contents of the flask carefully and then we
labelled our standard solution
, Figure 1: The exact amount of 2.65 g of sodium carbonate (s) in a weighing boat on the weighing
scale (calibrated)
